With popularization and rapid development of the Internet, especially development of commercial application services of the Internet, a network-based information requirement rapidly increases, and therefore a stricter requirement is imposed on a processing capability, a response capability, and the like of a service providing device in a network. The service providing device may also be referred to as a server. The server needs to meet access requirements of mass user terminals and provide stable and favorable network application services for the user terminals. A manner of improving a processing capability of the server is using a cluster technology. A plurality of servers constitute a server cluster. The servers provide a same or similar network application service. The plurality of servers obtain relatively high processing capabilities and response capabilities through concurrent computing.
A load balancing technology is a key part of a cluster system. Generally, as shown in FIG. 1, a network element selector (which may also be referred to as a load balancer) is deployed in the front end of a server cluster. The network element selector distributes, in the server cluster based on a preconfigured balancing policy, a user request sent by a user terminal by using a host client endpoint (Host), to provide an application service for the user terminal.
The Stream Control Transmission Protocol (SCTP) is a new-generation transmission protocol, and implements transmission of a reliable end-to-end message flow oriented to an association. SCTP data transmission is in a basic unit of a chunk. Each SCTP packet includes an SCTP common header and at least one chunk. For example, the SCTP packet includes the SCTP common header and at least one data chunk used to transmit user data. FIG. 2A shows a format of an SCTP packet. FIG. 2B shows a format of a data chunk in an SCTP packet. The common header of the SCTP packet includes a source port number, a destination port number, a verification tag, and a checksum.
User data is encapsulated into a data chunk. If a length of the user data is relatively small, a plurality of chunks may be bundled (Chunk Bundling) in a same SCTP packet, in other words, a plurality of data chunks respectively corresponding to a plurality of user terminals share a common header. In the prior art in which a service is provided based on the SCTP, a network element selector identifies an identity of a user terminal by using a verification tag in a common header of an SCTP packet. Therefore, user data that is corresponding to a plurality of user terminals and transmitted in a same SCTP packet is allocated to a same server for processing. Consequently, load between servers is severely imbalanced.